Anti-Magic Shell

Contract

Aams is TFT CAbilityAntiMagicShell (parent AAsm). Aam2 and ACam are AbilityData aliases whose code is Aams, so they share CAbilityAntiMagicShell and read their own rows through abilityitem_t.code.

Authored DataC selects the shell kind:

Rawcode	Archive	DataC	Buff applied	Effect
`Aams`	ROC and TFT	0	`Bams`	cannot be targeted by spells; `S_SpellDamage` is rejected
`ACam`	ROC and TFT	0	`Bams`	same immunity; creep cost/tooltip row
`Aam2`	TFT melee	300	`Bam2`	unit stays targetable; spell damage consumes the pool

ROC AbilityData.slk omits BuffID. The strings table still names Bams, so an empty BuffID with empty DataC applies Bams. TFT rows author BuffID1=Bams,Bam2; empty DataC uses the first token, non-zero DataC uses the second. Do not treat DataA/DataB as the shield amount for unit AMS.

Item Instant Shell (`Aami` / `AIxs`)

Aami is TFT CAbilityAntiMagicShellInstant (parent Aams). There is no AbilityData alias row for Aami itself; item AIxs authors code=Aami and is the live AbilityData row. Anti-Magic Potion (pams) uses abilList=AIxs, cooldownID=Aami, uses=1, perishable=1. Ubertip: immunity to magical spells for <AIxs,Dur1> seconds.

Rawcode	Archive	Notes
`Aami`	class only	register for `FindAbilityForCommand` / cooldownID; no AbilityData row
`AIxs`	ROC and TFT	item Instant AMS; `code=Aami`; not an `Aams` alias

Field	ROC `AIxs`	TFT `AIxs`	MetaData
`targs` / `cost` / `rng`	`air,ground` / 0 / 0	same	unit-target item use (`AB_SPELL`)
`cool` / `Dur` / `HeroDur`	0 / 90 / 90	30 / 15 / 15	item row owns duration
`DataA`	0	0	Ixs1 Damage To Summoned Units
`DataB`	0	10	Ixs2 Magic Damage Reduction
`DataC`	0	0	Ams3 Shield Life → empty applies `Bams`
`BuffID`	empty	`Bams,Bam2`	empty + DataC=0 → `Bams` fallback

AIxs / Aami share CAbilityAntiMagicShellInstant, which reuses the same Bams/Bam2 apply and S_AntiMagicShellAbsorb paths as unit AMS (DataC selects the buff). DataA summon damage and DataB magic-damage reduction are authored but not wired into damage yet (same gap as unit Ams1/Ams2).

Data Flow

AbilityData.slk (Aams / Aam2 / ACam)
  -> DataC, Dur/HeroDur, BuffID, targs, Cost, Rng
CAbilityAntiMagicShell
  -> unit_addtimedstatus(Bams or Bam2)
AbilityData.slk (AIxs, code=Aami) + class Aami
  -> item Dur/Cool/DataB/DataC/BuffID via abilityitem_t.code
CAbilityAntiMagicShellInstant
  -> same Bams/Bam2 apply + S_AntiMagicShellAbsorb as unit shell
S_UnitSpellImmune
  -> Bams only (Avatar also uses this predicate)
S_SpellDamage
  -> reject Bams; S_AntiMagicShellAbsorb consumes Bam2.remaining
S_ResolveAttackHit / T_Damage
  -> physical damage is not absorbed

Remaining Bam2 absorption is heroabilitystatus_t.data on the Bam2 slot. It is part of the raw edict_t save record. Recasting Aam2 replaces the buff and resets the pool to authored DataC. Overflow damage after the pool hits zero applies through T_Damage and S_SpellDamage returns true so other spell effects (stun, etc.) may proceed. Fully absorbed hits return false.

Aams targs are air,ground (no allegiance filter). Aam2 targs include friend,self, so enemies are invalid. Cast-capacity validation must delegate allegiance to S_SpellAllowsTarget; a hardcoded friendship check would incorrectly reject ROC-style unrestricted shells and custom enemy masks. anti_magic_shell_respects_authored_enemy_target_mask casts an authored enemy-only shell through S_CastUnitTargetSpell; the Aam2 test also verifies that a friendly-only mask rejects the same cast.

Diagnostic Workflow

build/bin/ability_audit -data 'data/Warcraft III' -raw Aams
build/bin/ability_audit -data 'data/Warcraft III' -raw AIxs
build/bin/ability_audit -data 'data/Warcraft III' -raw Aami

Verification

make test-wc3-engine WC3_PATTERN='wc3_spell.anti_magic_shell*'

Focused tests cover Bams targeting immunity, physical pass-through, recast rejection while immune, expiry, the ROC missing-BuffID fallback, Aam2 absorption/overflow/refresh, unit alias procedure sharing, item AIxs/Aami Instant procedure lookup with authored item duration/DataC→Bams, and save/load of the remaining Bam2 pool.